ExportFactory - not able to find export

I am using ExportFactory to instantiate export dynamically but when I run my application ... it gives me error while composing parts in program.cs class shown below:

The composition remains unchanged. The changes were rejected because of the following error(s): The composition produced a single composition error. The root cause is provided below. Review the CompositionException.Errors property
for more detailed information.

1) No valid exports were found that match the constraint '((exportDefinition.ContractName == "ExportFactoryApp.Factories") AndAlso (exportDefinition.Metadata.ContainsKey("ExportTypeIdentity") AndAlso "ExportFactoryApp.Factories".Equals(exportDefinition.Metadata.get_Item("ExportTypeIdentity"))))',
invalid exports may have been rejected.